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CVE-2026-63818

HIGHCVSS 8.4/10EPSS 0.13%

Last modified

CVE-2026-63818 is a high-severity vulnerability rated 8.4/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: f2fs: validate orphan inode entry count f2fs_recover_orphan_inodes() trusts the orphan block entry_count when replaying orphan inodes from the checkpoint pack. A corrupted entry_count larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the ino[] array and interpret footer or following data as inode numbers. On a crafted image, mounting an unpatched kernel can drive orphan recovery into f2fs_bug_on() and panic the kernel. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: validate orphan inode entry count f2fs_recover_orphan_inodes() trusts the orphan block entry_count when replaying orphan inodes from the checkpoint pack. A corrupted entry_count larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the ino[] array and interpret footer or following data as inode numbers. On a crafted image, mounting an unpatched kernel can drive orphan recovery into f2fs_bug_on() and panic the kernel. Validate entry_count before consuming entries so corrupted checkpoint data fails the mount with -EFSCORRUPTED and requests fsck instead. Set ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be recorded in the superblock s_errors[] field. This gives fsck a persistent hint even though mount-time orphan recovery failure may leave no chance to persist SBI_NEED_FSCK through a checkpoint.

Metrics

CVSS 3.1
8.4/10

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.13%

3.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < 210c210c92d78fdf5051bc55c5c69044b1a2150a; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < ad101d15716f5a24d1fa82a849f80430c805a3dd; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < d2f236196d542ccd8505736e41c3a1d3f0305f6f; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < 550511a2470f6d204fa07b331f048bd2d3c51280; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < 8aad54746c251f2c2370118df766c0c82e2d2091; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < 2e12381d4495dc8b0ff042c6856022b2e359835c; >= 127e670abfa7fa150f6550d620ded930f5bdb4e7, < 846c499a65816d13f1186e3090e825e8bb8bcb8b
LinuxLinux3.8

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-63818?
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate orphan inode entry count f2fs_recover_orphan_inodes() trusts the orphan block entry_count when replaying orphan inodes from the checkpoint pack. A corrupted entry_count larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the ino[] array and interpret footer or following data as inode numbers. On a crafted image, mounting an unpatched kernel can drive orphan recovery into f2fs_bug_on() and panic the kernel. Validate entry_count before consuming entries so corrupted checkpoint data fails the mount with -EFSCORRUPTED and requests fsck instead. Set ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be recorded in the superblock s_errors[] field. This gives fsck a persistent hint even though mount-time orphan recovery failure may leave no chance to persist SBI_NEED_FSCK through a checkpoint.
How severe is CVE-2026-63818?
CVE-2026-63818 has a CVSS score of 8.4/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2026-63818?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST